1. Field of the Invention
The present invention relates generally to filtering systems, and more particularly, but not by way of limitation, to an improved apparatus and method for filtering contaminated fluid in fish tanks, aquariums, ponds, fountains, water treatment facilities, water purification devices and the like.
2. Brief Description of the Related Art
Many types of fluidized beds are known in the art. For example, U.S. Pat. No. 4,322,296 discloses a method for waste water treatment in a vessel having a fixed perforated plate and a movable perforated plate. A particulate carrier having a specific gravity greater than water is employed as the filtering medium within the vessel.
As a further example, U.S. Pat. No. 5,453,183 discloses a fluidized bed biological filter system for fish tanks. This system utilizes glass beads having a specific gravity greater than 1.5 times that of water as particulate media.
In these filtration systems, contaminated water is passed through a negatively buoyant particulate medium. Thus, these systems only accomplish one type of filtration, i.e., filtration through a particulate carrier having a specific gravity greater than water.